The tornadic thunderstorm events during the 1998-1999 South African summer

Abstract

Due to the occurrence of several tornadoes in the summer of 1998/99 it was decided to research the occurrence of tornadic events over South Africa. A general overview of tornadoes is given along with a way to classify the intensity of these events. This is followed by a section on the frequency, occurrence and location of tornadoes over South Africa. Severe weather and/or tornado events can be expected when certain atmospheric conditions prevail. These are defined and indications of threshold values for severe weather are given. Three tornadic events which occurred in 1998/99 in South Africa are then discussed by means of these parameters. The first is the Harrismith tornado in November 1998 which was classified as an F3 tornado by the Fujita-Pearson (FP) classification. The tornado which occurred in Mount Ayliff in January 1999 was seemingly the most severe ever reported - FP classification F4 - and was the next case considered. Finally a short summary on the Umtata event of December 1998 is given.

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